primary coolant chemistry - international atomic … coolant chemistry: fundamentals &...

Primary Coolant Chemistry: Fundamentals & Developments Nov. 2008 1/ 89> Proprietary of AREVA NP GmbH • Disclosure not permitted

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Primary Coolant Chemistry: Fundamental Aspects & Improvements/Optimizations


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Content of presentation

> Water chemistry: Fundamental aspects & requirements Material compatibilityControl of radiation fieldFuel compatibility

> Developments in chemistry control program:Siemens designed PWRs (SG with I800 Tubing) versa all other PWRs (SG with I600/690 tubing)

Radiation field control:pH/Li control strategies; EBA-ChemistryControl of radiolysis / Material Compatibility:Hydrogen additionZinc chemistry:Radiation field control; Material compatibility

> Primary Coolant Chemistry:Fundamentals & Developments ( November 2008) < 3/ 89

The

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Primary coolant chemistry Fundamental aspects & requirements:

Material compatibilityControl of radiation field

Fuel compatibility


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Objective of Coolant Chemistry

1 Reactor Pressure Vessel2 Steam Generator3 Main Coolant pump4 Pressurizer5 Pressurizer release Tank

Coolant has a function of:• Moderator / neutron reflector• Heat transfer from core to SG

Coolant Chemistry functions:• Core Reactivity Control

Boric acid chemical “shim” for reactivity control

• RCS IntegrityReducing conditions (preventing water radiolysis)+ Impurity control to prevent stainless steel & I600 PWSCC (I690TT, I800 are immune against PWSSC)

• Fuel IntegrityLimit Li concentration & optimized pH operationto prevent fuel clad corrosion & crud deposition

• Radiation Field ControlOptimized pH operation to minimize corrosion product release, activation & transport

For the selection of chemistry the materials, design & operating conditions of RCS, especially the key components should be considered

Requirements to coolant chemistry:• Material compatibility• Radiation field control


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Materials Used World wide in Reactor Coolant System

RCS Materials exposed to coolant have in general high corrosion compatibility:* Components: Austenitic stainless steel* Loop piping: Austenitic stainless steel* Fuel Cladding: Zircaloy, M5, Zirlo* SG Tubing: I 800, I 600 (MA, TT), I 690TT* In small amount: Stellite and Cr-Steels

Key Components:Reactor Pressure Vessel Steam Generator




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Materials Used Worldwide in Reactor Coolant System

Alloy Compositions

0% 20% 40% 60% 80% 100%

304SS

308SS

309SS

316SS

321SS

347SS

Inconel 600

Inconel 690

Icoloy 800

Inconel 718

Stellite 6

Zircaloy-4

ZIRLO

Zr 1%NB

Zr 2.5% Nb

CrNiFeMnCoZrMoTiNbSnCuW

Material CombinationSt

ainl

ess

Stee

l

SG T

ubin

gFu

el C

ladd

ing

Ref: K. Garbett, IAEA-Seminar Karlsruhe, 2006


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How Coolant Chemistry Fulfills These Objectives?Chemical Additives to Coolant

> Coolant alkaline & reducing conditions are achieved by addingLithium-7 Hydroxid for optimum pHT control• Minimizing the Corrosion Product transport / Radiation Field Control• Minimizing the Fuel cladding corrosion (Limitation of Li-concentration)

Hydrogen to achieve • Reducing conditions / suppressing the water radiolysis• To influence the corrosion product solubility

(to improve Radiation Field Control)

> Impurity control to avoid selective type of corrosion byOperating Coolant Purification System,

Consumables control (especially during annual outages)

> Boric acid is added for neutron absorption as required by core reactivity control during different operating modes


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Fundamental Aspects of Coolant Chemistry / Alkalinity

Optimum pHT -Value for Radiation Field Control


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Fundamental Aspects of Coolant ChemistryMetal Release Rate of RCS Materials

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

0 1000 2000 3000 4000 5000 6000 7000 8000

Test Duration (hours)

Met

al R

elea

se R

ate

(mg.

dm-2

.mo-

1)

Stellites Stainless Steel Alloy 690 Alloy 800

Alloy 690

SS

Alloy 800

Stellites

RCS materials are in general corrosion resistant low metal release rates

Metal release rates of different main RCS materials

Even though, the extreme small amount of released corrosion products (CP) can be deposited and activated in the core; causing:* Radiation field increase in RCS* Increased risk for fuel corrosion


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Fundamental Aspects of Coolant ChemistryMechanism of Radiation Field Built-up

Mechanism of radiation field build-up:1st step: CP release from out of core areas

(especially from SGs)2nd step: Transport with coolant3rd step: CP deposition in Core4th step: Activation of CPs in Core5th step: Re-release of activated CPs into

coolant & transport6th step: Deposition of activated CPs out of

Core areaIncrease of Radiation Field

Radiation field increase by incorporation of 58Co & 60Co in the Spinels

Reactor pressure vessel Steam generator

Reactorcoolantpump

Incorporation ofCo60, Co58 insystem surfaces

Coolant

Coolantpurification

In-coreactivation

Metal release(Fe, Ni, Co, Cr, ...)

58Co & 60Co are the main responsible activated CP for Radiation Field (RF).

58Co & 60Co sources :58Ni (n,p) 58Co Mainly SG tubing59Co (n,γ) 60Co Stellite, SG tubing

58Co t1/2: ~ 70 days dominates RF in early plant life60Co t1/2: ~ 5.24 years dominates RF later


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Fundamental Aspects of Coolant ChemistrySG Tubing Material as Corrosion Product Source

SG tubing material with highest surface area is the main source of the corrosion products (CP) in RCS.

Based on field experience the CPs are a mixture of* Ni Ferrites* Ni oxide and metallic Ni

Their composition depends on SG tubing material:* I 600 / I 690 are Ni based materials more Ni & NiO can be expected* I 800 as Fe based material produces less Ni, NiO containing CPsThis fact to be considered for selection of optimum pHT control program

~0.53>1.7>3.6Ni / Fe+Cr~0.81>6.4>9.0Ni / Fe

20.0 – 23.028.0 – 31.014.0 – 17.0Cr32.0 – 35.0>58.0>72.0Ni

~40.1 – 43.17.0 – 11.06.0 – 10.0FeIncoloy 800Inconel 690Inconel 600Element

Chemical Composition


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Fundamental Aspects of Coolant ChemistryChemical Composition of RCS Oxide Layers

The solubility of RCS oxide Spinels depends on Temperature and pH-value

Solubility of Magnetite Solubility of Ni-Ferrite

Past assumption: RCS oxide layers consists mainly of Fe3O4

Recent knowledge: RCS oxide layers consists mainly of Ni-Ferrites(NixFe3-xO4,CoyFe3-yO4 and NixCo yFe3-(x+y)O4)


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Fundamental Aspects of Coolant ChemistryTemperature influence on pH-value

6,9

7

7,1

7,2

7,3

7,4

7,5

7,6

280 290 300 310 320 330Temperatur [°C]

pH

~ 292°C7,04

7,47

~ 326°C

In Europe pHT is defined at 300°C; in several other countries it is defined at Taverg (plant specific; e.g. 308.6 °C)

For pHT definition it is needed to consider the temperature


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Fundamental Aspects of Coolant ChemistryCoolant pH Values as a Function of Temperature

4

5

6

7

8

9

10

11

0 50 100 150 200 250 300 350

Temperatur [°C]

pH-W

ert

Pure Water

1000 mg/kg Bnat

1,4 mg/kg Li

1000 mg/kg Bnat und 1,4 mg/kg Li

Water alone or Water + Boric Acid don‘t have the pH value, to achieve the solubility minimum of RCS oxide layers, necessary for radiation field control!

Addition of alkalizing agent, 7LiOH,is necessary.

Influence of Temperature on pH-value

7LiOH is selected instead of natural LiOH:

More Tritium production due to 6Li (n,α) 3H


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Fundamental Aspects of Coolant ChemistryStrategy for pHT Control

pH 6.7

pH 6.8

pH 6.9

pH 7.0

pH 7.1 pH 7.2pH 7.3 pH 7.4 pH 7.5 pH 7.6

0

1

2

3

4

5

6

0200400600800100012001400160018002000B concentration [ppm]

Li c

once

ntra

tion

[ppm

]

pH300°C

pHT Control Strategy: * Oxide solubility minimum in entire RCS

Demand to increase the pHT (6.9 7.4)* Considering fuel cladding compatibility

Lithium concentration / pHT limitation

pHT-value as Function of Li- & B-concentration

Variation of pHT-chemistry control programs6 6,5 7 7,5 8 8,5

pH(300° C)

Lösl

ichk

eit v

on M

agne

tit u

nd N

icke

lfer

NickelferritMagnetit

Sol

ubilit

y of

mag

netit

e &

Ni-F

errit

e

Li limitation due to material compatibility considerations


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tion.

Fundamental Aspects of Coolant ChemistryLithium & Fuel Clad Compatibility

10 100 1000

1

10

100

Isothermal, non-leachable Li Ramasubramanian McDonald Framatome ANP

Isothermal, total Li Pecheur Kido Framatome ANP

Fact

or o

f Li-e

nhan

ced

corr

osio

n ra

te

Li-content of the oxide layer (ppm)

Enriched Li concentration in fuel deposits can cause cladding corrosion

Coolant Li concentration is therefore limited by fuel vendors

Field experience:* Most experience

with Li: 2 ppm* Sufficient amountof experience up to 3.5 ppm

* Few experiencewith 5-6 ppm


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on, a

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Fundamental Aspects of Coolant ChemistrySolubility of Fe in Ni-Ferrites

Fe Solubility in Nickel FerritespH chemistry refers to a pH defined at 300 °C

3

4

5

6

7

8

9

6 6,2 6,4 6,6 6,8 7 7,2 7,4 7,6 7,8 8

pH(T)

solu

bilit

y of

Fe

[ppb

]

pH(296°C) pH(328°C)

7.2 h i t

7.4 chemistry

Optimum pHT for Fe: ~ 7.4

Core inlet

Core outlet


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Fundamental Aspects of Coolant ChemistrySolubility of Ni in Ni-Ferrites

Ni Solubility in Nickel FerritespH chemistry refers to a pH defined at 300 °C

0,2

0,3

0,4

0,5

0,6

0,7

6 6,2 6,4 6,6 6,8 7 7,2 7,4 7,6 7,8 8

pH(T)

solu

bilit

y of

Fe

[ppb

]

pH(296°C) pH(328°C)

7.2 chemistry 7.4 chemistry

Ni solubility higher at core outlet

Core inlet

Core outlet


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Fundamental aspects of Coolant chemistry /Hydrogen Addition:

Reducing Conditions/Suppressing of Water Radiolysis


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Fundamental Aspects of Coolant ChemistryHydrogen Addition

The objective of hydrogen adding:

Influences the corrosion product solubility in a positive way with respect to “Radiation Field Control”

* Suppressing the water radiolysis * Counteracting the risk of selective type of corrosion, which might be causedby oxidizing species


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Fundamental Aspects of Coolant ChemistryHow much Hydrogen is needed to Control Radiolysis

Plot of H2O2 concentration against H2 concentration for 0 boron

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

0.1 1 10 100[H2]/cc kg-1

[H2O

2]/p

pm

25C100C150C200C300C

Plot of H2O2 concentration against H2 concentration for 1800 ppm boron

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

1.00E+03

0.1 1 10 100[H2]/cc kg-1

[H2O

2]/p

pm

25C100C150C200C300C

Necessary hydrogen concentration to suppress the radiolysis:

0 ppm Bor

1800 ppm Bor

Radiolysis calculations:* At 300°C: > 0.09 ppm (1 cc)* At: 25°C: > 0.9 ppm (10 cc)

Plant measurements:* NPP Belleville : > 0.45 ppm (5 cc)* NPP Gösgen: > 0.43 ppm (4.8 cc)* NPP Obrigheim: ~ 0.5 ppm (5.6 cc)

Guide line values: Germany: 2 – 4 ppm H2 (22.4 – 44.8 cc)World wide: 25 – 50 cc H2

(Selected based on calculations at 25°C)

Ref: K. Garbett, IAEA-Seminar Karlsruhe, 2006


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Primary coolant chemistry Improvements and Optimizations:

Material compatibilityControl of radiation field

Fuel compatibility


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Improvements & Optimization ofPrimary Coolant Chemistry

C o r ro s io n p ro d u c ts

re le a s e d fro m S G tu b in gC o rro s io n p ro d u c ts a c t iv a te d in re a c to r c o re

C o rro s io n p ro d u c ts

d e p o s i t o u t o f c o re

Experience in the early days of PWR operation:

* Crud transportation SG Reactor Core* Heavy crud build-up on fuel surfaces

This resulted in:* High radiation fields on out-of-core surfaces,* Fuel performance compromised,* Even in several PWRs Coolant flow disturbances∆p problems in reactor core

World wide need for coolant chemistry improvements to counteract these problems!!!


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Improvements & Optimization ofPrimary Coolant Chemistry

Siemens designed PWRsSG tubing material: I 800

Coolant chemistry improvements:World wide two main approaches due to used Steam generator tubing materials

W, CE, B&W, FA and MHI designed PWRsSG tubing material: I 600, I 690

1:1.9 – 1:2.11.8:12.8:1Ni:(Fe+Cr)20.0 – 23.028.0 – 31.014.0 – 17.0Cr (%)32.0 – 35.0>58.0>72.0Ni (%)

~40.1 – 43.17.0 – 11.06.0 – 10.0Fe (%)Incoloy 800Inconel 690Inconel 600Element

SG Tubing Materials

Oxide film growth on I 800 does not result in the formation of large quantities of excess nickelAdditional aspect:I 800 & I 690 are immune against PWSCC but I 600 not!

Facts to be considered:


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Primary Coolant ChemistryEPRI Guidelines for W, CE and B&W Designed PWRs

(SG Tubing: I 600 /T 690TT)

1 2 3

Chloride (ppb) 3/week (typical)Plant specific

limit >150 >1500

Fluoride (ppb) 3/week (typical) Plant specific limit

>150 >1500

Sulphate (ppb) 1/week Plant specific limit

>150 >1500

Lithium (ppm) 3/week Defined by pH programme

- -

<25 <15>50 <5

Dissolved Oxygen (ppb)Defined in

Tech.Specs. >5 - >100

Diagnostic Parameter Sample FrequencyConductivity (µS/cm, 25°C) 1/day

pH (25°C) 1/dayBoron (ppm) 1/day

Suspended Solids (ppb) 1.weekSilica (ppb) 1/week

Zinc (ppb)Defined in zinc

addition programme

To establish and trend changes from Plant-specific target <3000 ppb

As required by plant-specific programme

Assess consistency with additivesReason for Analysis

Assess consistency with additivesAs required for reactivity control

Action LevelControl Parameter Sample Frequency

Hydrogen cc(STP)/kg 3/week

Ref: Garbett, IAEA Workshop Karlsruhe, 2006 Revision 5


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Primary Coolant ChemistryEdF Guidelines for Framatome Designed PWRs

(SG Tubing: I 600 /T 690TT)

Ref: Nordmann, IAEA Workshop, Karlsruhe, 2006


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Primary Coolant ChemistryVGB Guidelines for Siemens Designed PWRs

(SG Tubing: I 800)

Ref: Odar, etal, Jeju Island, 2006


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Occupational Radiation Exposure per Plant and Year

0

1

2

3

4

5

6

7

8

1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000Year

Col

lect

ive

dose

per

pla

nt a

nd y

ear i

n m

an-S

v France

USA

Japan

All Siemens PWRs

Siemens pre-Convoy PWRs

Siemens Convoy PWRs

Nuclear industry has been successful in reducing radiation exposures of PWRs within the past decades

Ref: Guinard et al. Berlin 2008

Extremely low radiation exposure (< 0.5 ManSv/a) experienced in German Pre-Convoy and Convoy PWRs (Stellite free plants)


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.


Siemens Designed PWRs (SGs with I 800 tubing material)


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Historical Development of Innovations regardingPrimary System Design and Primary Coolant Chemistry at

German PWRs

Impr

ovem

ents

Implementation of 7Lithium-hydroxide1-2 ppm Lithium chemistry

1971/72

Implementation of Hydrogen Injection1972/73

Identification of Main Radiation Sources (Reactor Pressure Vessel or Steam Generator ?)Qualification of Stellite Replacement MaterialImplementation of Stellite Replacement Material

(In-Core and Out-Of-Core) in New Plants

1975 to 1985

Implementation of Zinc InjectionStart of Enriched Boric Acid Application

since 1995

2003............

Qualification and Implementation of I-800 SG Material

1969 to 1975

Start of Coordinated Coolant Chemistry1975/76

Start of Modified Coolant Chemistry1984/85


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry Improvements:Strategy for pHT Control

at Siemens Designed PWRs


Variation of pHT-chemistry control programs

pH 6.7

pH 6.8

pH 6.9

pH 7.0

pH 7.1 pH 7.2pH 7.3 pH 7.4 pH 7.5 pH 7.6

0

1

2

3

4

5

6


Li c

once

ntra

tion

[ppm

]

pH300°C0

0.5

1

1.5

2

2.5

01.07.83 29.09.83 28.12.83 27.03.84

Date

Li (

mg/

kg)

0

0.5

1

1.5

2

2.5

07.07.05 05.10.05 03.01.06 03.04.06

Date

Li (

mg/

kg)

1-2 ppm Li Chemistry

pH300: 6.9 Coordinated Li Chemistry

Modified Li Chemistry


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Typical Coolant Chemistry in a German PWR with EBA (320 d cycle)

0

0,5

1

1,5

2

2,5

0200400600800100012001400

boron concentration [ppm]

lithi

um c

once

ntra

tion

[ppm

]

Improvements in Coolant ChemistryGerman pHT Control Program

modified chemistry

coordinated chemistry

BOC boron conc. for nat. BA

BOC = begin of cycle, nat. BA = natural boric acidEBA = enriched boric acidT = 300 °C / 572 °F

BOC boron conc. for EBA

6,0

6,5

7,0

7,5

8,0

0 50 100 150 200 250 300 350 400

Operation Days

pH30

0°C

Plant APlant EPlant LPlant Q

Non EBA Cycles

EBA Cycles

6,0

6,5

7,0

7,5

8,0

0 50 100 150 200 250 300 350 400

Operation Days

pH30

0°C

Plant APlant EPlant LPlant Q

Non EBA Cycles

EBA Cycles

pH300: 6.9

pH300: 7.4

0

0,5

1

1,5

2

2,5

050100150200250300350400450500550600650700

B [mg/kg]

Li [m

g/kg

]

7,1

7,2

7,3

7,4

7,5

7,6

pH [300°C

]

Li = 2,0 + 0,1 ppm

pH bei 300 °C

315 mg B/kg

200 0


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Improvement of Material Concept:Replacement of Stellite by Improved Hardfacing Material

Siemens Designed pre-Convoy and Convoy Plants

Hold Down Plates

Control Rod Drives

Alignment for Grid plate

Radial Core Stop

Support

Irradiation Channel

Control Rod Guide Assembly

Core Barrel Reactor Alignment

Areas with Co-Base Alloys

NowFormer

Entire Hard-faced Area

Co-baseAlloy

Co-baseAlloy

Control RodDrives

Core Area

1.46 m² 1.46 m²

1.59 m² 0.03 m²

1975 to 1985

Example: RPV Internals

Reason: Reduction of Co sources(Stellite is the main Co source)


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry in GermanyResults of pHT Increase

1,00E+04

1,00E+05

1,00E+06

1,00E+07

1,00E+08

1,00E+09

1,00E+10

01.03.1982 25.11.1984 22.08.1987 18.05.1990 11.02.1993 08.11.1995 04.08.1998 30.04.2001 25.01.2004

Bq/

m³

-240

-180

-120

-60

0

60

120Load [%

]

Co-58Co-60Load

Change pH7,0 coord.. to pH7,4 mod.

1,00E+04

1,00E+05

1,00E+06

1,00E+07

1,00E+08

1,00E+09

1,00E+10

01.03.1982 25.11.1984 22.08.1987 18.05.1990 11.02.1993 08.11.1995 04.08.1998 30.04.2001 25.01.2004

Bq/

m³

-240

-180

-120

-60

0

60

120Load [%

]

Co-58Co-60Load

Change pH7,0 coord.. to pH7,4 mod.

0

0,5

1

1,5

2

2,5

0200400600800100012001400

Boron [ppm]

Lith

ium

[ppm

]

Specifications: Li: < 2.2 ppmH2: 2-4 ppmCl: < 0.1 ppmO2: < 0.005 ppm

Modified Chemistry

Coordinated Chemistry

Coordinated Chemistry Modified Chemistry

Dose rate improvements

Decrease of coolant 58Co

Increase of pHT resulted in: * Reduction of 58Co in

Coolant* Reduced field radiation

Solubility minimum of Spinel oxides

6 6,5 7 7,5 8 8,5pH(300° C)

Lösl

ichk

eit v

on M

agne

tit u

nd N

icke

lferr

it NickelferritMagnetit

Magnetite Ni-Ferrite

pHT: 6.9 pHT: 7.4

0

0,5

1

1,5

2

2,5

3

3,5

4

0 2 4 6 8 10 12 14Cycle No.

Dose Rate [mSv/h]

Plant I, coord. - none

Plant K, mod. - none

Plant L, mod. - 46 %

Plant M, coord. - 76 %Plant N, mod. - 79 %

Plant O, mod. - 79 %

Plant Q, mod. - 76 %

Co-replacem.

B/Li-chem.Coordinated

Chemistry

Modified Chemistry

StellteiPWRs

} Co arm PWRs

Primary Coolant Chemistry: Fundamentals & Developments Nov. 2008 > Proprietary of AREVA NP GmbH • Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Optimization of Primary Coolant Chemistry at Siemens Designed PWRS

pHT-Control Using EBA

0

1

2

3

4

5

Li [p

pm]

1200800480300240

1000667400250200

800533320200160

600400240150120

40026716010080

200133

805040

0 ppm B natural B0 ppm B 30 % B-100 ppm B 50 % B-100 ppm B 80 % B-100 ppm B 100 % B-10

pH < 7,4Li < 2 ppm(see full lines)

100 % B-10

natural B (20 atom-% B-10)

50 % B-10

30 % B-10

80 % B-10

German PWRs

pHT control using Natural and Enriched Boric Acid

Target pHT : 7.4

EBA:Option to operate for long time at higher pHT for radiation field control

Due to power up-rates and increased core duty EBA is introduced


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Hydrogen Control Band at German PWRs

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0

C D F A B G E I K M H L N O P QPlants

H2

Con

cent

ratio

n [c

c/kg

]

Low Duty Plants Medium Duty Plants High Duty Plants

Plant DH cycle averages:DH concentration values: 18 – 40 cc DH/kgAverage DH concentration: ~ 30 cc DH/kg

VGB Guideline Revisions1982: 22 – 44 cc DH/kg2007: 17 – 44 cc DH/kg


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry AppliedDifferent Core Duties

1968 1972 1976 1980 1984 1988 1992 1996 2000 2004

1-2 ppm Li strategyCoordinated ChemistryModified Chemistry (MC)PHWR-ChemistryMC + DZOMC + EBAMC + EBA + DZO

Stade

Borssele

Biblis A

Biblis B

Obrigheim

Unterweser

Neckarwestheim2

Neckarwestheim1

Gösgen

Philippsburg 2

Isar 2

Emsland

Grafenrheinfeld

Grohnde

Angra 2

Brokdorf

Trillo

Atucha 1

Low Duty Plants:

Medium Duty Plants:

High Duty Plants:

Ext. High Duty Pl t

HDCI

<120

120-150

>150

>200

1 PWR: Coordinated Chemistry (pHT: 7.0)16 PWRs: Modified Chemistry (pHT: 7.4)

8 PWRs: DZO Chemistry9 PWRs: EBA Chemistry3 PWRs: DZO + EBA Chemistry 11 High Duty Plants


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Fuel Deposits at German PWRs Visual Inspection Results

Medium Duty Plant (HDCI: 140) High Duty Plant (HDCI: 326)

No visual fuel deposits, not only in low / medium duty plants but also in high duty plants


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.


W, CE, B&W, MHI, FA Designed PWRs(SGs with I 600, I 690 tubing materials)


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

US PWR Historical Chemistry Trends

Hydrogen Management

Fruzzetti, Jeju Island 2006

elevated constant pH (7.3/7.4)

ultrasonic fuel cleaning


zinc injection

modified elevated lithium program

elevated lithium program

constant pH 6.9

’75 ’80 ’85 ’90 ’95 ’00 ‘05

EPRI Water Chemistry Guidelines


ultrasonic fuel cleaning


zinc injection

modified elevated lithium program

elevated lithium program

constant pH 6.9

’75 ’80 ’85 ’90 ’95 ’00 ‘05

EPRI Water Chemistry Guidelines


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.


Radiation Field ControlLi/pH Control Strategies


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry Improvements:Strategy for pHT Control

at US & Other PWRs with I600/I690 SG Tubing


Variation of pHT-chemistry control programs

pH 6.7

pH 6.8

pH 6.9

pH 7.0

pH 7.1 pH 7.2pH 7.3 pH 7.4 pH 7.5 pH 7.6

0

1

2

3

4

5

6


Li c

once

ntra

tion

[ppm

]

pH300°C

Coordinated Chemistry

Elevated Chemistry

Elevated Modified Chemistry

Modified Chemistry

Longer cycles demands higher Li concentrations at BOC, in order to have pH300 ≥ 6.9

More corrosion resistant fuel cladding materials (Zirlo, M5) enable increase of Li concentration

As of 2008 field experience exists with up to 6 ppm Li (Comanche Peak PWRs)


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry Improvements:Different Strategies for pHT Control (1)

00.5

11.5

22.5

33.5

44.5

55.5

66.5

77.5

8

0500100015002000Boron, mg kg-1

Lith

ium

, mg

kg-1 pH 7.2

Co-ordinated pH Chemistry

pH 6.9

00.5

11.5

2

2.53

3.54

0500100015002000Boron, mg kg-1

Lith

ium

, mg

kg-1

Modified pH Chemistry

EDF Chemistry

pH 6.9

pH 7.0

pH 7.4

Coordinated pH ChemistrypHT: 6.9 and 7.2

Modified pH ChemistrypHT: 7.0, 7.2 and 7.4

Usually Li concentration is limited to 2 ppm at BOC

Due to extended cycle duration (12 m 18m), BOC Boron concentration had to be increased ~1200 ppm ~ 1800 ppm. Because of still Li limitation of 2.2 ppm, modified chemistry is introduced.


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry Improvements:Different Strategies for pHT Control (2)

Elevated or Elevated-Constant pH ChemistrypHT: 7.0, 7.2 and 7.4

0

0.5

1

1.5

2

2.5

3

3.5

4

0500100015002000

Boron, mg kg-1

Lith

ium

, mg

kg-1

Elevated pH Chemistry

pH 7.0

pH 7.4

0

0.5

1

1.5

2

2.5

3

3.5

4

0500100015002000

Boron, mg kg-1

Lith

ium

, mg kg

-1

Elevated or Elevated-Constant pH chemistry

pH 7.0

pH 7.4

Elevated:Li concentration > 2 ppm

Constant pH operation between 7.2 and 7.4 is expected to minimize the core crud deposition , fuel corrosion, radiation fields and AOA

Elevated pH ChemistrypHT: 7.0, 7.2 and 7.4

First introduced in Ringhals Units, followed by Milstone 3


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry Improvements:US PWR Experience with Elevated pH Chemistry

0

10

20

30

40

50

60

70

80

90

2001 2002 2003 2004 2005 2006

Year

Perc

enta

ge o

f Pla

nts

W

ithin

Ran

ge

<3.0 ppm 3.0 - 3.25 ppm >3.25 ppm

Number of US PWRs operating with elevated Li concentrations at BOC is increasing

Fruzzetti, Berlin 2008


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry Improvements:Comanche Peak Demonstration of Elevated pH/Li Chemistry

Lithium Behavior

0

1

2

3

4

5

6

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000

MWD/MTU

Lith

ium

(ppm

)

U2C6U2C7U2C8U2C9

RCS pH at plant Tav

6.80

6.90

7.00

7.10

7.20

7.30

7.40

7.50

7.60

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000

MWD/MTU

pH (@

Tav)

U2C6U2C7U2C8U2C9

0.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

0 1 2 3 4 5 6 7 8 9 10Outage

Dos

e R

ate,

Gy/

hr

Loop 1 Loop 2 Loop 3 Loop 4

SG Tube Bundle dose rates

Objective was to reduce* Radiation fields,* Susceptibility to AOA

Li control during last 4 cycles

pHT control during last 4 cycles

Stevens, Berlin 2008

Results:* No adverse trends either in the area ofchemistry or core performance

* No indications of AOA* Indications for improved radiation fields* No anomalous shutdown chemistry

EPRI Fuel Reliability Program, WG#1 September 6-7, 2006


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Coolant Chemistry Improvements:Ringhals Experience with Elevated pH Chemistry

Bengtsson, Berlin 2008

3

2

4

3

2

4

3

2

4

pH regimes (MC to EOC) in Ringhals Units

SG cold leg channel head dose rates

Co-58 Shut-down release

pH increase in Ringhals 2 & 3 resulted in decrease of* 58Co Shut-down release* SG channel head dose rates

Whereas in Ringhals 4 with lower pH the opposite is experienced


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.


Material Compatibility: Hydrogen Control Strategies

Fruzzetti, Jeju Island 2006

Identification of PWSCC in RPV Head penetrations in US PWRs lead to root cause investigation programs. It resulted in:* Reconsidering the

hydrogen control strategies.* Encouraging the use of zinc

injectionJones, San Francisco 2004


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

PWSCC Susceptible Alloys in W-PWRs

Alloys 600, 182, 82 locations in W-PWRs

Ref: Jones, Intr. Water Chem. Conf. San Francisco, 2004

Li, B and pHT are observed to have almost no influence on PWSCC CGR. But DH!!!


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Current Industry Operating Hydrogen Ranges

Current operating limit is 25-50 cc/kg and EPRI is assessing an increase up to 80 cc/kg

RCS Operating Hydrogen Ranges Chemistry Monitoring Data Assessment 2002 - 2006

1

33

38

14

0

43

61

13

1 00

10

20

30

40

50

60

70

25-29 30-34 35-39 40-44 ≥45

Cycle Average RCS Hydrogen Range (cc/Kg)

Num

ber o

f Cyc

les

in R

ange

US International

Ref: Fruzzetti, Berlin 2008


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Effect of Dissolved Hydrogen on the Crack Growth Rate of Alloy X - 750

Effect of H2 on the crack growth rate of Alloy X-750 in 360oC water

Reference: Andersen, et al., International Conference on Water Chemistry of Nuclear Reactor Systems, Jeju Island Korea, Oct. 2006

00.20.40.60.8

11.21.41.61.8

0 50 100 150

Hydrogen Concentration (cc/kg)

Cra

ck G

row

th R

ate

(mils

/day

)

Ni MetalNiO

H2 Specs

H2 operating range

Temperature & DH dependence of PWSCC

Reference: K. Sato, Dissolved H2 Workshop, Tohoku University, Japan July 2007

Increased PWSCC CGR at the Ni/NiO phase boundary observed


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Effect of Dissolved Hydrogen on PWSCC of Alloy 600Crack Growth Rate and Crack Initiation Rate

0

5000

10000

15000

20000

25000

0 5 10 15 20

Hydrogen activity, kPa

Cra

ck in

itiat

ion

time,

h

0,E+00

2,E-08

4,E-08

6,E-08

8,E-08

1,E-07

Cra

ck g

row

th ra

te, m

m/s

5 10 15 20 25 30 35

ml H2/kg H2O (330 °C)

Growth

Initiation

M67:5

M67:4M34:2

Reference: A. Molander, Dissolved H2 Workshop, Tohoku University, Japan July 2007

With increasing DH concentration:* Crack growth rates increase,* Crack initiation time decreases


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

US Approach:Increase of Coolant Hydrogen Concentration

Expected improvements by DH increase:

Andresen, etal, 13th Intern. Conf. on Optimization of DH in PWR Primary Coolant, Tohoku Univ, Japan, July 2007

Future considerations:* Investigationson adverse effect of DH increase:- Safety issues

(Post-LOCA considerations)- Fuel performance- Radiation fieldcontrol

* Stepwise increaseof DH

According to US mind:Increase of DH provides benefit, but lowering might be detrimental below 330°C


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Japanese Approach:Decrease of Hydrogen Concentration

Dozaki, 13th Intern. Conf. on Optimization of DH inPWR Primary Coolant, Tohoku Univ, Japan, July 2007

Sato, 13th Intern. Conf. on Optimization of DH inPWR Primary Coolant, Tohoku Univ, Japan, July 2007

Lab results:PWSCC initiation time delay and lower PWSCC susceptibility is expected by decreasing coolant H2 concentration


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Result of hydrogen decreasing:* NiO with high solubility becomes more stable * Decrease of fuel deposits * Decrease of Ni in fuel deposits (Ni/Fe Ratio)

(Less 58Co during S/D & Less dose)

Japanese field experience with decreasing the hydrogen concentration

Japanese Approach:Field Experience- Additional Benefits for Radiation Control


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Zinc ChemistryFor Dose Rate Reduction

MechanismDose Rate ReductionMaterial Compatibility

Field Experience


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Fundamental Aspects of Coolant ChemistryDiscovery of Zinc Influence on Dose Rate Build-up

BWR Dose Rate Field Experience

Plants with brass condenser tubes

Plants with stainless steel condenser tubes


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Fundamental Aspects of Coolant ChemistryDose Rate Mitigation by Zinc Chemistry

Reference: Nawrotsky & Kleppa, J. Inorg. Nucl. Chem., 1967, Vol. 29, p. 2701

Spinel Structur

Mechanism of Zinc ChemistrySite preference energies for spinels


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Zinc Chemistry:Dose Rate Reduction in German PWRs

Field experience at NPP Biblis

Unit B: SG-Chanel head

Unit A: SG Chanel head

0

50

100

150

200

250

300

1989 1991 1993 1995 1997 1999 2001 2003 2005Year

Dos

e ra

te [m

Sv/h

]

OutletInlet

Biblis B

Avg. values 1989-96Outlet: 213 mSv/hInlet: 190 mSv/h Zinc injection

0

50

100

150

200

250

300

1987 1989 1991 1993 1995 1997 1999 2001 2003 2005Year

Dos

e ra

te [m

Sv/h

]

OutletInlet

Biblis A

Avg. values 1987-98Outlet: 205 mSv/hInlet: 178 mSv/h Zinc injection

PWRs with I800 SG tubing


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Zinc Chemistry:Dose Rate Reduction in US PWRs

PWRs with I600 SG tubing

NPP Diablo Canyon

NPP Palisades

Reference: H. Ocken, et al., International Conference Water Chemistry in Nuclear Reactor systems, Chimie 2002, Avignon April 2002


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Zinc ChemistryNPP Angra-2: Zinc Chemistry from First Day on!

0

20

40

60

80

100

120

140

3-Loop, coord. 4-Loop, coord. 4-Loop, mod. 3-Loop, mod. Angra 2 pre-Konvoi,mod.

pre-Konvoi,coord.

Konvoi, mod.

DR

SG

Cha

nnel

Hea

ds, H

ot L

eg [m

Sv/h

]

full color: 1st Cyclehatched pattern: 3rd Cycle

0

0,5

1

1,5

2

2,5

4-Loop, coord. 4-Loop, mod. 3-Loop, mod. Angra 2 Pre-Konvoi,coord.

Pre-Konvoi,mod.

Konvoi, mod. Konvoi, mod. Konvoi, mod.

mSv

/hfull color: 1. cyclehatched pattern: 2. cyclecheckered pattern: 3. cycle

Cross-Over Average Contact Dose Rates at German Plants

Pipe wall thicknesses:Angra 2: 58 mm.Sister plants (4-loop coord and 4-loop mod): 50 mmAll other plants: 55 mm

In NPP Angra-2 Zn chemistry was applied from first day of criticality

Co free plants

Co containing plants

Angra2

Angra2Co free plants

Co containing plants

Due to Zn chemistry from day 1 on, Angra 2 has similar low field radiation like Co free plants!!!


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Zinc ChemistryMaterial Compatibility

Reference: D.H. Lister, Presentation at EPRI Robust Fuel Program, Feb. 2002

Zn Influence on dose rate build-up Zn Influence on material compatibility

0

2

4

6

8

10

12

14

16

18

mg/

m²d

Stellite 6 1810CrNi I600/I690 IX-750 Stellite 6 1810CrNi I600/I690 IX-750

Without Zn

With Zn

Corrosion Rate Metal Release Rate

Test conditions: 1200 ppm B 2.2 ppm Li 50 ppb Zn (as Zn borate) T = 330 °C t = 3.5 months

Reference: .N. Esposito, et al, 5th Int. Symposium on Environmental. Degradation of Materials in Nuclear Power Systems-Water Reactors, 1991,


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

PWR Fleet Injection History

0

10

20

30

40

50

60

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Uni

ts (#

) & P

erce

nt In

ject

ing

(%)

Percent of PWRs injecting Number of Units Injecting

PWRs with Zinc Application

2008 data is projected for end-of-year based on current information.

Application Worldwide

2008 U.S., Actual to date: 25 (36%)

2008 U.S., Actual + Projected by yr-end: 29 (42%)

Ref: Fruzzetti, Berlin 2008

Siemens PWRs: 7 on Zn Chemistry (44% of total; or 78% of Stellite-PWRs)


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Primary Coolant ChemistryConclusions (1)

> World wide alkaline and reducing coolant chemistry is applied forAdequate control of radiation fieldsMaintaining high material compatibility andHigh fuel performance

> Even all these coolant chemistry strategies look in general verysimilar, they differ in detail significantly due to used SG tubing materials

SG with I 800: No excess Ni in the fuel crud (Magnetite & Ni-ferrites)Coolant chemistry: Modified Li 2 ppm chemistry (pHT: 7.4);

DH: 2-4 ppm Even operating with high duty cores no AOA is experienced

No need for elevated Li & DH chemistryOlder Siemens PWRs (stellites!): Zn injection for radiation field control


The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

ent,

expl

oita

tion

and

com

mun

icat

ion

of it

s co

nten

ts w

ithou

t exp

ress

ed a

utho

rizat

ion

is

proh

ibite

d. C

ontra

vent

ion

enta

ils li

abili

ty fo

r the

pay

men

t of d

amag

es. A

ll rig

hts

rese

rved

in th

e ev

ent o

f pat

ent,

utilit

y m

odel

or o

rnam

enta

l des

ign

regi

stra

tion.

Primary Coolant ChemistryConclusions (2)

SG with I600/690: Excess Ni in the fuel crud; Extended cycles (18-24 months), high duty cores caused in several PWRs AOA, high radiation field and/or shut-down chemistry problems (particulate release).

Need for elevated Li/pH chemistry (pHT: 7.2 / 7.4)PWSCC sensibility of Nickel base alloys (A 600, 182, 82 and X-750) demands modification of coolant DH content

Need either to increase or decrease DH!

> Zinc injection is applied world wide in many PWRs with success

Dose rate reduction

Mitigating PWSCC

> Cycle extensions, increasing core duty remains world wide a challenge for coolant chemistry

primary coolant chemistry - international atomic … coolant chemistry: fundamentals &...

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